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Note: Session titles beginning with an asterisk (*) have student presenters.
AUTHORS: Michael J. Porta, Richard A. Snow – Oklahoma Department of Wildlife Conservation, Oklahoma Fishery Research Laboratory; Daniel E. Shoup, Department of Natural Resource Ecology and Management, Oklahoma State University
ABSTRACT: The Oklahoma Department of Wildlife Conservation (ODWC) stocks reservoirs throughout Oklahoma with saugeye to control overcrowded, stunted white crappie populations and to provide recreational fishing opportunities. ODWC relies on saugeye as a management tool, and they provide a valuable recreational fishery, so sacrificing fish regularly to remove otoliths for aging purposes may be counterproductive. A non-lethal means of obtaining age estimates for saugeye to describe population dynamics is desirable. Therefore, we compared aging precision between readers and structures (otoliths and dorsal spines), and compared age-based population parameters (growth, mortality, recruitment) derived from these age estimates. Aging structures were removed from 47 saugeye collected from Lake Thunderbird, Oklahoma via electrofishing. Aging precision was highest between readers for sectioned otoliths (100% agreement; CV = 0%) and whole otoliths (98% agreement; CV = 3.2%), whereas precision was poor for dorsal spine ages (50% agreement; CV = 22.3%). When comparing final agreed ages, sectioned otoliths and whole otoliths were in 100% agreement, however otolith and spine agreement was 14%. Age bias plots indicate that final agreed spine ages always were higher than the agreed ages from otoliths. Because age assignments from the two structures were dissimilar, the corresponding mortality rates, growth models, and recruitment patterns were vastly different. We conclude that dorsal spines are not an appropriate aging structure for saugeye in Oklahoma, as age estimates lack precision and produce apparently erroneous population parameters. Fisheries managers should sacrifice saugeye for aging, as otolith age estimates are precise and accurately describe population dynamics.
Tuesday October 31, 2017 9:20am - 9:40am EDT
French